Cabbage palmetto (Sabal palmetto) is the most northerly
and abundant of the native tree palms. Other names sometimes used
are Carolina palmetto, common palmetto, palmetto, and
cabbage-palm. This medium-sized unbranched evergreen palm
commonly grows on sandy shores, along brackish marshes, in
seacoast woodlands of Southeastern United States and throughout
peninsular Florida. It can tolerate a broad range of soil
conditions and is often planted as a street tree. Abundant fruit
crops provide a good supply of food to many kinds of wildlife.

Habitat

Native Range

Cabbage palmetto is the most widely distributed of our native palm
trees. Its range extends northward from the Florida Keys through
its epicenter in south-central Florida to Cape Fear, NC. A
disjunct population has been reported at Cape Hatteras, NC (16).
From North Carolina south to the Florida line it hugs the
coastline, usually occurring within 20 km (12 mi) of the ocean.
In Florida, its northern boundary turns west through Gainesville
and follows an ancient shoreline across the peninsula to the Gulf
Coast. It then follows the shoreline westward to St. Andrews Bay
where its range is slowly extending (3). Outside the United
States, it is found in the Bahama Islands (23).

-The native range of cabbage palmetto.

Climate

The climate within the natural range of cabbage palmetto is
principally subtropical to warm temperate, humid, with an average
annual rainfall of 1000 to 1630 mm. (39 to 64 in) and average
annual minimum and maximum temperatures from about -4° to 36°
C (25° to 97° F). Low winter temperatures apparently
limit the horticultural range of the species, which now extends
more than 160 km (100 mi) north and inland of its natural range
(3).

Soils and Topography

Cabbage palmetto can tolerate a broad range of soil pH, salinity,
and drainage but prefers neutral to alkaline soils characterized
by near-surface or exposed calcareous sands, marls, or limestone
(10,15). Although it grows at the edges of both saline and
freshwater areas, it cannot survive lengthy tidal inundations (8)
but can withstand fluctuations of 2 m (6 ft) in freshwater levels
by developing extensive adventitious rootlets along its trunk up
to the high-water mark. This cylindrical root mass may reach
diameters of 1.8 to 2.4 rn (6 to 8 ft) (24).

In the northern part of its range, cabbage palmetto is primarily
found on the bay side of coastal dunes and adjacent mainland.
Farther south in Georgia, it extends up the flood plains of major
rivers. In central Florida, the tree is often found on fine sandy
soils with subsoils of limestone or marl on periodically flooded
lowlands, and on relic inland dune ridges below 30 rn (100 ft),
an elevation that defines the approximate shoreline of the
Wicomico Sea of the Pleistocene (7). With the construction of
drainage ditches in south-central Florida, it has colonized the
once seasonally inundated interhammock glades.

The species is found on a wide range of soils including those in
the orders Entisols, Alfisols, Ultisols, and Spodosols in south
Florida. Drainage tends to be restricted, ranging from somewhat
poorly to very poorly drained. All soils appear to have one
characteristic in common, a high calcium content, which is
indicated by either a high base saturation (Alfisols) or
limestone, phosphatic rock, or sea shells in the profile. Soil
series typical of the Alfisols are Boca, Bradenton, Parkwood, and
Riviera. Typical Entisols are exemplified by the Pompano series.
Charlotte, Oldsmar, and Wabasso soil series are typical Spodosols
on which the species is found.

The species often forms pure stands up to about 10 ha (25 acres)
in freshwater areas, called river hammocks if they lie along a
river, and cabbage-palm hammocks or palm savannas if they are on
inland prairies.

Associated Forest Cover

In the forest cover type Cabbage Palmetto (Society of American
Foresters Type 74), the species usually makes up a plurality of
the stocking (11). Because cabbage palmetto can accommodate a
wide range of sites, it is found in association with many plant
species, especially in south Florida. It is found on severe sites
such as dunes, salt flats, barrier islands, cactus thickets, and
wet prairies. It is a common component of such diverse
communities as freshwater cypress swamps, relic inland dune
ridges, and rockland pine forests, where it grows with South
Florida slash pine (Pinus elliottii var. densa) and
various tropical hardwoods on limestone outcrops. Other
coniferous associates include typical slash pine (P.
elliottii var. elliottii), pond pine (P.serotina),
and loblolly pine (P.taeda) at edges of
marshes; longleaf pine (P.palustris) on dry
sites such as xeric hammocks; and eastern redcedar (Juniperus
virginiana) in hydric hammocks. Cabbage palmetto is also a
component of both temperate and subtropical hardwoods, which
include species such as the various evergreen oaks (Quercus
spp.), loblolly-bay (Gordonia lasianthus), redbay
(Persea borbonia), magnolias (Magnolia spp.),
sweetgum (Liquidambar styraciflua), red maple (Acer
rubrum), baldcypress (Taxodium spp.), pignut hickory
(Carya glabra), gumbo-limbo (Bursera simaruba), cocoplum
(Chrysobalanus Waco), Florida strangler fig (Ficus aurea),
Florida poisontree (Metopium toxiferum), and wild
tamarind (Lysiloma latisiliquum). The abundance of
cabbage palmetto within a given community is often related to the
site's fire history. Cabbage palmetto can survive fires that kill
other arborescent vegetation be cause of its deeply embedded bud
and fire-resistant trunk; it thus tends to form pure stands with
periodic burning (19,27,30).

Several naturalized exotics, namely casuarina (Casuarina
spp.), melaleuca (Melaleuca quinquenervia), coconut
(Cocos nucifera), and Brazil peppertree (Schinus
terebinthifolia), are now commonly associated with cabbage
palmetto-apparently at its expense-but it is too early to judge
the extent of their competition.

Life History

Reproduction and Early Growth

Flowering and Fruiting- Flowers are perfect, about 6 mm
(0.25 in) in diameter by 3 mm (0.125 in) long, and creamy to
yellowish white (19,29). The showy flowers are borne in profusion
in arching or drooping clusters 1.5 to 2.5 m (5 to 8 ft) long,
from April through August in south Florida but for only a 4- to
6-week period beginning in the middle of July in North Carolina
(3,31). The fragrant flowers are pollinated by bees, although
other insects may be of local importance (3). The fruits are
black, fleshy, drupelike berries, 5 to 13 mm (0.2 to 0.5 in) in
diameter and averaging about 10 mm (0.4 in), each containing a
single, hard, brown, spherical seed (2,3).

Seed Production and Dissemination- The fruits mature in
the fall and persist on the spadix until removed by wind, rain,
or birds such as ring billed gulls, fish crows, cardinals, and
blue jays. Once on the ground, the fruits are eaten by numerous
animals or cached by rodents; such caches result in dense patches
of seedlings (3,14,19). In near-coast situations, however, the
major means of dissemination appears to be by water. The
distribution of cabbage palmetto along the Atlantic shoreline is
attributed to the seed's buoyancy and tolerance of saltwater.
Thus, the range of cabbage palmetto is a function of the speed
and direction of estuarine and littoral currents along a
shoreline. This fact explains the species spread northward along
the Atlantic Coast and its expansion westward along the Gulf
Coast (3).

Cabbage palmetto produces large numbers of fruits and seeds each
year. In a cabbage-palm hammock in southwest Florida, an
estimated 1,530,000/ha of ripe fruits (620,000/acre) were
produced per year, of which 9 percent contained intact seeds
after 6 months, 1 percent were infested by beetles, and 89
percent had been totally consumed or removed from the site (19).

Predation of cabbage palmetto seeds by a bruchid beetle (Caryobruchus
gleditsiae) is the major cause of seed loss and regeneration
failure (3,32). When seeds are carried off by animals, the
probability of predation by this insect is greatly reduced. Seeds
falling into water also escape this predation because they tend
to be covered by sand or organic debris, so that germination
occurs when temperature and moisture conditions become favorable.
However, infestation of the fruit while still on the tree is
substantial and can reach 98 percent (5). Seeds exposed to the
sun for long periods do not germinate well (3).

Germination of cabbage palmetto seeds is hastened by
stratification in moist sand for 30 days at 3° C (37°
F) (18). Dormancy is also broken if the micropyle cap is removed.
For example, germination of untreated seed was 36 percent in 100
days but was increased to 84 percent or more in 4 days by removal
of the micropyle cap (29). Moisture and temperature requirements
for germination are satisfactorily met throughout its range.
Although the species does not reproduce on the fore dune or beach
face, substrate salinity levels encountered on the lee side of
dunes or in upper reaches of tidal creeks and marshes do not
represent an establishment problem (3).

Seedling Development- Germination of cabbage palmetto is
hypogeal. Like other palms, it grows upward from a single
terminal bud and outward from the fibrovascular bundles
distributed throughout its trunk. Because seeds germinate from
middle to late summer, seedling growth the first year normally
consists of a primary root, one fully expanded leaf with stem
growth obliquely downward forming the rhizome. Ecotypic
differences between northern and southern seed sources in
seedling photosynthetic and biomass growth rates have been
observed (3).

Vegetative Reproduction- No information available.

Sapling and Pole Stages to Maturity

Growth and Yield- Since palms do not have a cambium as
such, they do not produce annual growth rings. Cabbage palmetto
reaches its maximum development in south-central Florida, but
good growth also occurs along the Gulf Coast to the Apalachicola
River. Mature trees are straight, unbranched, with heights from
10 to 25 m (33 to 82 ft) and diameters of 30 to 61 cm (12 to 24
in) (21). A dense well rounded crown is almost always formed. On
many trees the leaf bases or "boots" remain securely
attached while on others they slough off, leaving a fairly smooth
trunk (fig. 3). Diameters are exaggerated when these boots remain
attached to the trunk. Average growth rates are unknown. One
specimen, planted as an ornamental in south-central Florida, grew
to a height of 9 m (30 ft) and a diameter including boots of
about 76 cm (30 in) in 16 years (6).

Few stand measurements of cabbage palmetto have been made; stem
counts, in the rockland pine forest of Everglades National Park
(28) and in the sandy marl pine-palm association (4) and the
mixed swamp forest of the Big Cypress National Preserve (27),
showed cabbage palm to be rather abundant, with stems numbering
900/ha (364/acre), 500/ha (202/acre), and 180/ha (73/acre),
respectively. In a cabbage-palm hammock just north of the Big
Cypress Swamp, the count of cabbage palmetto was 1,010/ha
(409/acre), with a basal area of 53.0 m² /ha (231 ft²/acre);
there were 7,150 palm seedlings per hectare (2,895/acre) under
breast height (19).

Rotting Habit- The underground stem of cabbage palmetto is
short and bulbous, surrounded by a dense mass of contorted roots
commonly 1.2 to 1.5 m (4 to 5 ft) in diameter and 1.5 to 1.8 rn
(5 to 6 ft) deep. From this mass, tough, light-orange roots often
almost 13 mm (0.5 in) in diameter penetrate the soil for a
distance of 4.6 to 6.1 m (15 to 20 ft) (22).

Reaction to Competition- Cabbage palmetto is classed as
shade tolerant and is probably a climatic climax as well as a
fire climax. Since intensive management of cabbage palmetto has
not been tried, the effects of various silvicultural treatments
are conjectural. But its management would appear to be simple and
straightforward, with the tree managed in either pure or mixed
stands under either an even-or all-age management system.

Damaging Agents- In its native environment, only a rising
sea level, hurricanes, and organic soil fires are harmful to this
species. It is apparently free of damaging insects and most other
pathogens, although bole cankers have been reported (26). Seed
predation by the bruchid beetle, as previously discussed, would
be a major problem but for the large number of seed produced each
year.

South of the Tamiami Trail, which crosses the lower part of south
Florida, cabbage palmetto mortality is significant because
extensive drainage schemes, resulting in a reduced freshwater
head, have combined with a rising sea level to produce increased
salinities (1,8). Cabbage palmetto has been rated the most
wind-resistant south Florida tree but it nevertheless suffered
extensive damage from Hurricane Donna in 1960, particularly on
Palm Key in Florida Bay (9). Cabbage palmetto growing on organic
soil or deep humus deposits are killed by fire burning in this
organic layer because of root mortality and loss of mechanical
support. The extensive use of these trees in urban landscaping is
depleting native stands of mature cabbage palmetto, suggesting a
future need to manage stands for this use.

Special Uses

Cabbage palmetto is so called because of its edible terminal bud
which tastes somewhat like that vegetable. The bud, also called
swamp cabbage, is good both raw and cooked and is commercially
canned and sold. Removal of the bud kills the tree, however.
Cabbage palmetto was an important tree to the Seminole Indians,
who often made their homes on cabbage-palm hammocks (23). They
made bread meal from the fruit, which has a sweet, prunelike
flavor, and they used the palm fronds to thatch their chickees
(huts) and to make baskets (10,22,25). Many other uses of this
tree are documented (17,22,26): pilings for wharfs because they
resist attacks by seaworms, stems, hollowed out to form pipes for
carrying water, ornamental table tops from polished stem
cross-sections, canes, scrub brushes from the bark fibers and
leaf sheaths, and logs for cribbing in early fortifications
because they did not produce lethal splinters when struck by
cannonballs.

Currently, young cabbage palmetto fronds are collected and shipped
worldwide each spring for use on Palm Sunday. This tree is in
flower when many other plants are not and is a significant source
of a strong but delicious dark-amber honey.

Perhaps the most important uses are as an ornamental and as
wildlife food. The sheer magnitude of its annual fruit crop is
such that it provides a substantial part of the diet of many
animals such as deer, bear, raccoon, squirrel, bobwhite, and wild
turkey (12,13, 18, 19, 20).

Genetics

The only available information on varieties pretains to growth
differences between seedlings at Smith Island, NC, and Miami, FL.
Both the biomass and the photosynthetic rate of the Miami
seedlings were more than twice that of the Smith Island plants,
differences that were statistically significant (3).